Electrical fuse



Oct. 27,1925. 1,559,226

H. DAVIES ELECTRICAL FUSE Filed Jan. 26, 1920 HGIZ V/ 11 2 a 1 J 5 Z ZZ 19 12 J; A? J 10 1222 8 8 12 7 /1, 2 71;: IX/Z L INVENTOR:

f/OJ Vfl/FD DAV/ES,

Patented Oct. 27, 1925.

v UNITED STATES PATENT OFFICE.

HOWARD DAVIES, OF PHILADELPHIA, PENNSYLVANIA.

ELECTRICAL FUSE.

, Application filed January 26, 1920. Serialm. sums.

To an whom it may 00.1mm:

Be it known that I, HOWARD DAVIES, a at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented a certain new 'and useful Improvement in Electrical Fuses,'whereof the .following is a specification, reference being had to the accompanying drawing.

My invention relates to fuses of the generalclass including a tubular casing of insulating material having metallic termi nals at its opposite ends adaptfid to detachably secure a strip of fusible metal, and having means to electrically connect such fuse strip with conductors leading to and from said casing; and relates-to the specific class of such fuses contemplated in my copending application Serial No. 332,213 for. Letters Patent of the United States, in that.

the terminals comprise wedge abutments which are respectively fixed in the fuse casing at opposite ends thereof and adapted to co-operate with wedges which are movable in 7 said casing in. opposition to the respective abutments, to detachably secure the opposite ends of a fuse strip between them. However, in the structurcs described in that application, the movable wedges are independent of the fuse casings and provided with circumferential grooves, which the operator may engage with" a screw driver or similar implement adapted to be used as a lever to pry the wedges out of said casings when it is desired to renew the fuse, whereas, in accordance with my present imprve-. ment, the movable wedges maybe so connected with the terminal screw caps which are parts of the terminal fuse casings that 4 the operator may remove them with said caps byjsimply unscrewing the latter, and without the employment of any other implement.

Moreover, my invention includes various novel features of'construction andarrangemnt hereinafter more definitely specified, particularlywith reference to the construction and arrangement of the means for bold- Said screw caps in normalposition.

tion of a fuse embodying my invention.

Fig. II is a longitudinal sectional view of said fuse taken on line II, IIin Fig. I. v Fig. III is an end view of said fuse as shown in Fig. I.

n'th e' drawing; Figs-I is a side ele'vataken 011- the line VII, VII in Fig. V.

Referring to the form of my invention shown in Figs. I to III inclusive; the cylindrical tubular casing 1 is composed of insulating material, conveniently vulcanized fiber, and has the metallic screw nipples 2 threaded therein at its opposite ends and fastened with the respective set screws 3 which also hold the semicylindrical metallic wedge members 5 which have their inner faces 6 extending in planes which are oblique to the axis of said casing 1, so as to afford respective wedge abutment-s, in 'opposition to theparallel plane inclined faces 8 of the res ective com lementary semicylindrical wedges 9. Sai wedges 9 are movable axially in said casing 1, to clamp the respective ends of the fusestrip 10 between said wedges 9 and said wedge abutments 5, but in contact with the elements 12 with which said abutments are faced, as shown in Fig. "II. As indicated in dotted dinesin Fig. I, said fuse strip 10 is much wider at its cnds, which are engaged with the wedge elements aforesaid, than atits intermediate portion; the latter being of a cross sectional area which is precisely predetermined in accordance with the rated caacit of the fuse. Such capacity is manieste by marks on each strip appearing exterior to said casing as shown in Fig. III. Said wedges 9 may be pressed into the position shown in FigrII, b rotation of the terminal screw caps 11 w ich have internal screw threads engaging said nipples 2; the inclination of said plane faces of the wedge members aforesaid being such 100 strip 10 which are engaged by the respective I terminals.

- Said abutments 5 are provlded with sepaableconstruction, WhlCh are indicate at 13 I wedges axially, without turning said wedges;

cap flange 19.

I find it convenient to provide each of said wedges 9 with a rivet lug 15, which extends through the two metallic washers 16 and 17, respectively inside and outside of the inwardly extending annular-flange 19 of the respective cap 11 at the left hand side of Fig. II, so that. although said cap flange 19 may turn freely between said washers, such turning movement causes said flange to thrust upon one or the other of said washers and shift said wedge 9 accordingly. In order to hold said washers in concentric relation I find it convenient to also couple them by rivets 21. I also find it convenient to interpose a packing washer 22, of insulating material, such as asbestos composition, between said washers 16 and Y17 and said ca flan e 19, which prevents the outlet of ame'i rom the casing when the fuse blows. However, it is to be understood that such insulating washers 22 may be omitted, without impairing the function of said washers 16 and 17. Moreover, as illustrated at the right hand side of Fig. II; all of said washers 16, 17 and 22, may be omittedyin' which case the wedge 9 may be operatively connected directly with the terminal cap by p means of the lug 29 extending from the wedge 9 and overlapping the edge of the Of course, such a fuse as above described,

. with reference to Figs. I to III inclusive,

may be made without the blade elements 12, if the fuse is to be included in a circuit by connection at each end between spring lates bearing directly upon said caps 11.

owever, for a fuse of that latter type, I prefer to further simplify the construction, as shown in Figs. ,IV and V, wherein the cylindrical tubu ar casing 31 is composed of insulatin material, for instance, vulcanized fiber, an has the metallic screw nipples 32 at its opposite ends, which are not threaded therein like the nipples 2 aforesaid, but have respective annular flanges 33 and 34 extending over said casing 31. As best shown at the left hand side of Fig. V, the flange 33 is internally screw threaded to engage an external screw thread on the easing 31, but, as shown at the right hand side of Fig. V, the flange 34 is not internally screw thread -d but is smoothly cylindrical and merely fitted over the adjacent endof the casing 31. Said screw nipples 32 are fastened with respective rivets 36 which extend through the respective flanges 33 and 34 and the adjacent wallof the casing 31 and also hold the semic lindrical metallic wedge members 37 whic have their inner faces 38 extending in planes which are oblique to the axis of said casing 1, so as to -turn freely, with respect to said wedges,

wedge members 37 and 41 aforesaid being such as to afford adequate" clamping action throughout the entire surfaces of said fuse strip 42 which are engaged by the respective terminals. I find it convenient to provide each of said wedges 41 with a screw 45 which extends axially through the adjacent cap 43 so that although said caps may such turning movement causes said caps to thrust said wedges in or draw. them out in accordance with the direction of the turning movement, thus lessening the cost of construction by the omission of the washers 16, 17 and 22 and their appurtenances-above described. Therefore, it appears that fuses "embodying my invention may be made in. at

least four different ways above contemlated, to wit, first, a fuse having both ends like the left hand end of the fuse shown in Fig. II; second, a'fuse having both ends like the ri ht hand end of, the fuse shown in Fig. II;

Fig. V'and, fourth, a fuse having both ends like ihe r irght hand end of the fuse shown in 1g.

Therefore .I 'do not desire to limit myself to the precise details of construction and arrangement herein set forth, as it is ob-' vious that various modifications may be made therein without departing from the essential features of my invention as defined p in the appended claims.

I claim:

1. In an electrical fuse structure; the combination with a cylindrical tubular cas; ing of insulating material, having screw threads at its opposite ends; of metallic screw nip les at said ends; means fastening said nipp es, including respective elements extending radially through said casing and said nipples; substantially semicylindrical metallic terminal members held in said nipples by said fastening means and having their inner faces extending in planes which are oblique to the axis of said casing, afiording respective wedge 'abutments; wedges respectively axially movable in said casing in opposition to said wedge abutments, having their inner faces respectively inclined parallel with the inclined faces of said abutments; whereby said wedges are adapted to third, a fuse having both ends like 100 i the left hand end'of the fuse shown in are held in alinement with each other b said abutments; and a fuse strip exten ing in said casing, having its opposite ends clamped by said wedge members.

2. In an electrical fuse structure; the combination with a tubular casing of insulating material, having screw threads at its opposite ends; of metallic screw nipples on said casingat its opposite ends; means fastening said nipples, including respective elements extending radially in said casing and said nipples; substantially semicylin- .drical metallic terminal members held in said nipples by said fastening means and having their inner faces extending in planes which are oblique to the axis of said casing, affording respective wedge abutments; wedges respectively axially movable in said casing in'opposition .to said wedge abutments, having their inner faces respectively inclined parallel with the inclined faces of said abutments; whereby said wedges are ada ted to clamp a fuse strip; each of said we ges having means to effect its withdrawal, including a projection at the outer end thereof; screw caps respectively fitted to the outer ends of said nipples; each having an inwardly projecting annular flange engaging the adjacent wedge projection; whereby each of said wedges is removable by turning the cap with which it is connected but is separable from said cap when withdrawn from said casing; and a fuse strip extending in said casing, having its lqpposite ends clamped by said wedge memrs. '3. In an electrical fuse structure; the

, combination with a tubular casing of insulating material; of metallic screw nipples on said casing at its opposite ends; means fastening said ni ples, including respective elements extending radially in said casing and said nipples; substantially semicylindrical metallic terminal members held in said nipples by said fastening means and having their inner faces extending in planes which are oblique t0 the axis of said casing, affording respective wedge abutments; wedges respectively axially movable in said casing in opposition to said wedge abutments, having their inner faces res ectively inclined parallel with the inclined faces of said abutments; whereby said wedges are adapted toclarnp a fuse strip; each of said wedges having means to efi'eet its withdrawal, including a projection at the outer end thereof; screw caps respectively fitted to the outer ends of said nipples; each having an inwardly projecting annular flange engaging the adjacent wedge projection; and a fuse strip extending in said casing, having its opposite ends clamped by said wedge members.

- 4. In an electrical fuse structure; the combination with a tubular casing of insulating material; of metallic screw nipples on said casing at its oppositeends; metallic terminal members in said nip les having their inner faces extending in pl aines which are oblique to the axis of said casing, affording respective wedge abutments; wedges respectively axially movable in said casing in opposition to sa d wedge abutments; whereby said wedges are adapted to clamp a fuse strip between them and their respective abutments; each of said wedges having means to effect its withdrawal, including a rojection from the outer end thereof; an screw caps respectively fitted to the outer ends of lic screws at its opposite ends; of terminal -members in said screws havlng their inner faces extending in planes which are oblique to the axis of said casing, affording respective wedge abutments; wedges respectively movable in said casing in opposition to said wedge abutments whereby said wedges are adapted to clamp a fuse strip between them and their respective abutments; each of said wedges having means to effectits withdrawal, including a projection from the' outer end thereof; screw caps respectively fitted to the outer ends of said screws; each detachably engaging the adjacent wedge projection; whereby each wedge may be removed by turning its cap.

6. In an electrical fuse structure; the combination with a casing having hollow metallic screws at its opposite ends; of terminal members in said screws having their inner faces extending in planes which are oblique to the axis of said casing, affording respective wedge abutments; wedges respectively movable in said casing in opposition to said wedge abutments; whereby said wedges are adapted to clamp a fuse strip between them and their respective abutments; each of said wedges having means to effect its withdrawal, including a projection from the outer end thereof; screw caps respectively fitted to the outer ends of said screws; each engaging the adjacent wedge projection; whereby each wedge may be removed by turning its cap.

7. In an electrical fuse structure; the combination with a cylindrical tubular casing of insulating material; of externally threaded hollow metallic screws at opposite ends of said casing, each having a cylindrical flange overlapping the end of said casing; means fastening said screws on said casing, including elements extending radially in said flanges and said casing; terminal members in said screws having their inner faces ex tending in planes which are oblique to the axis of said casing, affording respective wedge abutments; wedges respectively movable in said casing in'opposition to said wedge abutments; whereby said wedges are adapted to clamp a fuse strip between them and their respective abutments; each of said wedges having means to effect its withdrawal, including an element projecting from the outer end thereof; screw caps respectively fitted to the outer ends of said screws; each detachably engaging the adjacent element aforesaid projecting from the respective wedge; whereby each wedge may be removed by turning its cap.

8. In an electrical fuse structure; the combination with a'cylindrical tubular casing of insulating material; of externally threaded hollow metallic screws at opposite ends of said casing, each having a cylindrical flange overlapping the end of said casing; means fastening said screws on said casing, including elements extending radially in said flanges and said casing; terminal 1 members in said screws having their inner effect its withdrawal, including an element projecting from the outer end thereof; screw caps respectively fitted to the outer ends of said screws; each engaging the adjacent element aforesaid'projecting from the respective wedge; whereby each wedge may be removed by turning-its cap.

9. In an electrical fuse structure; the combination with a cylindrical tubular casing of insulating material; of externally threaded hollow metallic screws at opposite ends of said casing, each having a cylindrical flange overlapping the end of said casing; means fastening-said screws on-s aid casing, including elements extending .radially in said flanges and said casing; terminal members in said screws having their inner faces plane and extending in planes which are oblique to the axis of said casing, affording respective plane wedge abutments; plane faced wedges respectively movable in said 10. In an electrical fuse, structure; the

combination witha cylindrical tubular casing of insulating material; of externally threaded hollow metallic screws at opposite ends of said casing each having a cylin-' drical flange overlapping ,the end of said casing, and having a smooth cylindriform inner face; means fastening said screws on said casing, including elements extending radially in said flanges and said casing; terminal members in said screws having their inner faces extending in planes which are oblique to the axis of said casing, affording respective wedge abutments; and wedges respectivelymovable in said casing in opposition to said wedge abutments; whereby said wedges are adapted to clamp a fuse strip between them and their respective abutmentsi 11. In an electrical fuse structure; the combination with a casing having hollow externally threaded screws at its opposite ends; of terminal members in said screws having their inner faces extending in planes .which are oblique to the axis of said casing,

abutments; r

affording respective wedge wedges respectively movable in said casing in opposition to said wedge abutments whereby said wedges are adapted to clamp a fuse strip between them and their respective abutments; screw caps respectively fitted to the outer ends of said screws, rotatable independently of said wedges; and means connecting said wedges with said caps, whereby said wedges may be withdrawn by turning said caps.

12. In an electrical fuse structure; the combination with a relatively stationary wedge element; of a movable wedge element; a rotary screw cap, distinct from said wedge element; and means operatively connecting said wedge with said cap, arranged to permit rotation *of said cap with respect to HOEVARD 

